Integrated and DC-powered superconducting microcomb

TL;DR

This paper presents a fully integrated superconducting microcomb device that generates ultra-low power, coherent microwave frequency combs with narrow linewidths, advancing on-chip photonics and quantum processing applications.

Contribution

It introduces a novel superconducting microcomb system that is easy to manufacture, operates with ultra-low power, and achieves coherent, multi-octave microwave comb generation.

Findings

Comb spectrum spans multiple octaves in microwave domain

Linewidths of comb lines can be narrowed to 1 Hz

Power consumption as low as tens of picowatts

Abstract

Frequency combs, specialized laser sources emitting multiple equidistant frequency lines, have revolutionized science and technology with unprecedented precision and versatility. Recently, integrated frequency combs are emerging as scalable solutions for on-chip photonics. Here, we demonstrate a fully integrated superconducting microcomb that is easy to manufacture, simple to operate, and consumes ultra-low power. Our turnkey apparatus comprises a basic nonlinear superconducting device, a Josephson junction, directly coupled to a superconducting microstrip resonator. We showcase coherent comb generation through self-started mode-locking. Therefore, comb emission is initiated solely by activating a DC bias source, with power consumption as low as tens of picowatts. The resulting comb spectrum resides in the microwave domain and spans multiple octaves. The linewidths of all comb lines can be narrowed down to 1 Hz through a unique coherent injection-locking technique. Our work represents a critical step towards fully integrated microwave photonics and offers the potential for integrated quantum processors.